How hearing loss in old age affects the brain
April 23, 2020
Science Daily/Ruhr-University Bochum
If your hearing deteriorates in old age, the risk of dementia and cognitive decline increases. So far, it hasn't been clear why. A team of neuroscientists has examined what happens in the brain when hearing gradually deteriorates: key areas of the brain are reorganized, and this affects memory.
Daniela Beckmann, Mirko Feldmann, Olena Shchyglo and Professor Denise Manahan-Vaughan from the Department of Neurophysiology of the Medical Faculty worked together for the study.
When sensory perception fades
The researchers studied the brain of mice that exhibit hereditary hearing loss, similar to age related hearing loss in humans. The scientists analysed the density of neurotransmitter receptors in the brain that are crucial for memory formation. They also researched the extent to which information storage in the brain's most important memory organ, the hippocampus, was affected.
Adaptability of the brain suffers
Memory is enabled by a process called synaptic plasticity. In the hippocampus, synaptic plasticity was chronically impaired by progressive hearing loss. The distribution and density of neurotransmitter receptors in sensory and memory regions of the brain also changed constantly. The stronger the hearing impairment, the poorer were both synaptic plasticity and memory ability.
"Our results provide new insights into the putative cause of the relationship between cognitive decline and age-related hearing loss in humans," said Denise Manahan-Vaughan. "We believe that the constant changes in neurotransmitter receptor expression caused by progressive hearing loss create shifting sands at the level of sensory information processing that prevent the hippocampus from working effectively," she adds.
https://www.sciencedaily.com/releases/2020/04/200423130446.htm
Hearing loss tied with mental, physical, and social ailments in older people
July 19, 2019
Science Daily/University of Tsukuba
Hearing loss is the world's fourth-leading cause of years lived with disability. The condition may worsen an array of mental, physical, and social complications. As over 90% of hearing loss is age-related, its burden is notably growing amid aging populations.
Hearing ability is integrally tied with communication, and hearing loss leads to communication barriers. This in turn increases stress and restricts the ability to venture outdoors. It may also be tied with cognitive decline and dementia.
A team of Japanese researchers centered at the University of Tsukuba sought to shed further light on the relation of hearing loss and other illnesses among older people. They examined three key areas and found hearing loss had a clear link with all three, especially memory loss. The researchers reported their findings in the journal, Geriatrics & Gerontology International.
The team took advantage of the large-scale 2016 Comprehensive Survey of Living Conditions of Japan, a nationwide, population-based cross-sectional questionnaire of more than 220,000 households. From this, they targeted 137,723 survey respondents aged 65 or older and without dementia. The survey's self-reported responses on conditions including hearing loss allowed valuable comparisons to be made.
"Japan is the world's most rapidly aging country, and this is a large and compelling data set of its citizens," lead author Masao Iwagami says. "It was a solid foundation for examining correlations between hearing loss and three key problems: outdoor activity limitations, psychological distress, and memory loss."
About 9% of the 137,723 survey respondents examined had reported hearing loss. Their responses also showed the condition increased with age. The researchers further adjusted and refined their analysis to account for factors such as smoking, alcohol intake, and income. The differences between those with and without hearing loss were quite telling.
Of those reporting limitations in outdoor activities such as shopping or travel, 28.9% of those with hearing loss were affected vs. just 9.5% of those without. For psychological distress it was 39.7% vs 19.3%. For memory loss, the gap was the most profound: 37.7% vs 5.2%. These patterns were similar irrespective of age or sex.
"Hearing loss takes an enormous toll on older people in so many ways, physically and mentally, while limiting activities of daily living," study co-author Yoko Kobayashi says. "Greater awareness of the burden of hearing loss will help improve their quality of life. Measures such as hearing aids and social support by volunteers in the community can also provide them with assistance."
https://www.sciencedaily.com/releases/2019/07/190719102138.htm
With age comes hearing loss and a greater risk of cognitive decline
But study suggests higher education might counter effects of milder hearing impairment
February 12, 2019
Science Daily/University of California - San Diego
In a new study, researchers report that hearing impairment is associated with accelerated cognitive decline with age, though the impact of mild hearing loss may be lessened by higher education
Hearing impairment is a common consequence of advancing age. Almost three-quarters of U.S. adults age 70 and older suffer from some degree of hearing loss. One unanswered question has been to what degree hearing impairment intersects with and influences age-related cognitive decline.
In a new study, researchers at University of California San Diego School of Medicine report that hearing impairment is associated with accelerated cognitive decline with age, though the impact of mild hearing loss may be lessened by higher education.
The findings are published in the February 12, 2019 issue of the Journal of Gerontology: Series A Medical Sciences.
A team of scientists, led by senior author Linda K. McEvoy, PhD, professor in the departments of Radiology and Family Medicine and Public Health, tracked 1,164 participants (mean age 73.5 years, 64 percent women) in the longitudinal Rancho Bernardo Study of Healthy Aging for up to 24 years. All had undergone assessments for hearing acuity and cognitive function between the years 1992 to 1996 and had up to five subsequent cognitive assessments at approximately four-year intervals. None used a hearing aid.
The researchers found that almost half of the participants had mild hearing impairment, with 16.8 percent suffering moderate-to-severe hearing loss. Those with more serious hearing impairment showed worse performance at the initial visit on a pair of commonly used cognitive assessment tests: the Mini-Mental State Exam (MMSE) and the Trail-Making Test, Part B. Hearing impairment was associated with greater decline in performance on these tests over time, both for those with mild hearing impairment and those with more severe hearing impairment.
However, the association of mild hearing impairment with rate of cognitive decline was modified by education. Mild hearing impairment was associated with steeper decline among study participants without a college education, but not among those with higher education. Moderate-to-severe hearing impairment was associated with steeper MMSE decline regardless of education level.
"We surmise that higher education may provide sufficient cognitive reserve to counter the effects of mild hearing loss, but not enough to overcome effects of more severe hearing impairment," said McEvoy.
Degree of social engagement did not affect the association of hearing impairment with cognitive decline. "This was a somewhat unexpected finding" said first author Ali Alattar. "Others have postulated that cognitive deficits related to hearing impairment may arise from social isolation, but in our study, participants who had hearing impairment were as socially engaged as those without hearing loss."
The findings, said the authors, emphasize the need for physicians to be aware that older patients with hearing impairments are at greater risk for cognitive decline. They also emphasized the importance of preventing hearing loss at all ages, since hearing impairment is rarely reversible. One important way to protect hearing, they said, is to minimize loud noise exposure since this is the largest modifiable risk factor for hearing impairment.
https://www.sciencedaily.com/releases/2019/02/190212134802.htm
Exploring the connection between hearing loss and cognitive decline
Eight-year study reveals association that may indicate early stage changes in cognition
January 29, 2019
Science Daily/Brigham and Women's Hospital
Hearing loss affects tens of millions of Americans and its global prevalence is expected to grow as the world's population ages. A new study led by investigators at Brigham and Women's Hospital adds to a growing body of evidence that hearing loss is associated with higher risk of cognitive decline. These findings suggest that hearing loss may help identify individuals at greater risk of cognitive decline and could provide insights for earlier intervention and prevention.
"Dementia is a substantial public health challenge that continues to grow. There is no cure, and effective treatments to prevent progression or reverse the course of dementia are lacking," said lead author Sharon Curhan, MD, MSc, a physician and epidemiologist in the Channing Division for Network Medicine at the Brigham. "Our findings show that hearing loss is associated with new onset of subjective cognitive concerns which may be indicative of early stage changes in cognition. These findings may help identify individuals at greater risk of cognitive decline."
Curhan and colleagues conducted an eight-year longitudinal study among 10,107 men aged ?62 years in the Health Professionals Follow-up Study (HFPS). They assessed subjective cognitive function (SCF) scores based on responses to a six-item questionnaire administered in 2008, 2012 and 2016. SCF decline was defined as a new report of at least one SCF concern during follow-up.
The team found that hearing loss was associated with higher risk of subjective cognitive decline. Compared with men with no hearing loss, the relative risk of cognitive decline was 30 percent higher among men with mild hearing loss, 42 percent higher among men with moderate hearing loss, and 54 percent higher among men with severe hearing loss but who did not use hearing aids.
Researchers were interested to see if hearing aids might modify risk. Although the found that among men with severe hearing loss who used hearing aids, the risk of cognitive decline was somewhat less (37 percent higher), it was not statistically significantly different from the risk among those who did not use hearing aids. The authors note that this may have been due to limited power or could suggest that if a difference truly exists, the magnitude of the effect may be modest.
The authors also note that the study was limited to predominantly older white male health professionals. This allowed for greater control of variability but further studies in additional populations would be helpful. In addition, the study relies on self-reported hearing loss and subjective measures of cognitive function. In the future, the team plans to investigate the relationships between self-reported hearing loss, change in audiometric hearing thresholds, and changes in cognition in women using several different assessment measures.
"Whether there is a temporal association between hearing loss and cognitive decline and whether this relation is causal remains unclear," said Curhan. "We plan to conduct further longitudinal studies of the relation of hearing loss and cognition in women and in younger populations, which will be informative."
https://www.sciencedaily.com/releases/2019/01/190129081936.htm